You don't really have a good mental picture of how your political opponents think -- you're just running them as stereotype models and arguing with the stereotypes.

Just as a for example, if you actually paid attention to what they say and how they'd behave, you'd notice that Republicans, while supporting soldiers generally, don't like deserters (and especially deserters who badmouth the Army and the U.S.) specifically, and especially didn't like the idea of trading five high-ranking Taliban commanders for such a person. Their reaction to Bergdahl is therefore not particularly surprising.